[folks] docs: Fix installation directory for documentation

[Niels De Graef <nielsdg src gnome org>]

commit aebece7edb7ae86a6e48d4ba73554a87ccee6a6a
Author: Philip Withnall <withnall endlessm com>
Date:   Wed May 8 12:36:19 2019 +0100

    docs: Fix installation directory for documentation
    
    It has been wrong since the autotools times, and apparently nobody has
    noticed. Why bother documenting the library in the first place?
    
    Signed-off-by: Philip Withnall <withnall endlessm com>
    
    Fixes: #108

 docs/devhelp/meson.build | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/docs/devhelp/meson.build b/docs/devhelp/meson.build
index cb9e2782..968a9482 100644
--- a/docs/devhelp/meson.build
+++ b/docs/devhelp/meson.build
@@ -16,6 +16,6 @@ foreach doc_target : valadoc_targets
     ],
     depends: doc_target.get('library'),
     install: true,
-    install_dir: get_option('datadir') / 'devhelp' / 'references',
+    install_dir: get_option('datadir') / 'devhelp' / 'books',
   )
 endforeach